Synergistic inhibition mechanism of phosphate and phytic acid on carbon steel in carbonated concrete pore solutions containing chlorides

Synergistic inhibition performance of trisodium phosphate (TSP) and phytic acid (PA) on chloride-induced corrosion of Q235 carbon steel in carbonated concrete pore solutions was investigated using electrochemical measurements, XPS, AFM and SEM/EDS. At the optimum concentration ratio of TSP and PA, the mixed inhibitor showed an inhibition efficiency of 89.8 % after long-term chloride exposure due to the progressive formation of a protective oxide film with specific bilayer structure on the steel surface, and the corresponding synergistic in-hibition mechanism was proposed. However, the excessive content of PA could compete with TSP, thereby leading to an antagonistic effect with reduced inhibition efficiencies.

Automated summary

This study investigated the synergistic inhibition performance of trisodium phosphate and phytic acid on chloride-induced corrosion of Q235 carbon steel in carbonated concrete pore solutions using various techniques. The mixed inhibitor showed high inhibition efficiency due to the formation of a protective oxide film, but excessive phytic acid content competed with trisodium phosphate, leading to reduced inhibition efficiencies.